Asserting his role as a top surrogate for Donald Trump, Gov. Chris Christie opened the first day of the Republican National Convention chiding fellow Republicans who refused to back Trump as the party’s presidential nominee and portrayed him as a soft-hearted family man but an unequivocal leader.

As the party prepares to formally crown its polarizing candidate in the role of standard-bearer, Christie is interceding with a message for Republicans in Cleveland and voters across the country: Get behind Trump or get four more years of failed Democratic leadership.

For the first time since Trump denied him the running-mate role last Friday, Christie appeared in public saying that he approved of the selection of Indiana Gov. Mike Pence and that he was openly considering options for his political future.

Several times during a brief question-and-answer session with dozens of Michigan Republicans on Monday morning, Christie was asked if he would accept the job of attorney general in a Trump administration. Delegates also referred to Christie as the next attorney general and was even hypothetically put into the position by a man who asked Christie to promise to “prosecute Hillary Clinton” for her use of private email.

But those possibilities for Christie will only exist if Trump defeats Clinton, the presumptive Democratic nominee, this fall. A Monmouth University poll released Monday said Clinton holds a 3-percentage-point lead among registered voters and a 2-point lead over those most likely to vote, a narrowing between the two candidates as they prepare to accept their parties’ nominations this week and next.

The Republican Party entered its convention in Cleveland fractured over its anticipated nomination of Trump, whose campaign has been marked by inflammatory comments condemned from inside and outside the party as racist, bigoted and xenophobic.

Many of the party’s elder statesmen — notably both former Presidents Bush and 2012 nominee Mitt Romney — have declined to attend the convention and refuse to support Trump. Christie singled out former 2016 Republican candidates, but not by name, who are not supporting Trump after promising during the primary contest to back the party’s eventual nominee.

“I signed that pledge. It is unacceptable to me, and it should be unacceptable to you, that anyone who signed that pledge is not now adhering to that pledge,” Christie said to standing applause. He then delivered a line he has used repeatedly in recent days: “If you’re not working for Donald Trump, you’re working for Hillary. That’s the bottom line.”

Since endorsing Trump in February, Christie has publicly been one of his most loyal supporters. And that has given him an opportunity to maintain a presence in national politics and, in some ways, extend his own presidential campaign themes with sustained attacks on President Obama. While campaigning for Trump, Christie attacks Obama as a weak, ineffective leader and says electing Clinton would ensure another four years of the current administration.

Christie’s remarks to the delegates Monday came a day after three police officers were shot and killed in Baton Rouge, Louisiana, the second police slaying in two weeks as racial tensions have spread across the nation. Christie said the violence at home and abroad is “at least partially the product of a failure of American leadership.”

Christie said President Obama has said the right things in the wake of recent police shootings but faulted him for what he sees as insufficient support for law enforcement in the past and for being “largely silent” on “slaughter going on in Chicago,” the president’s hometown and a city beset by rampant gun violence.

“It is appalling,” Christie said. “And President Trump, I would advise him to go to Chicago and to stand up and say, I am for every law-abiding citizen in this city, no matter your race, your gender or your ethnicity, no matter your economic status or your educational background. I am for safety and security for every citizen.”

A woman tells Christie, 'please be the attorney general.' Christie: "That's very nice. That's very kind. We'll see what life brings."

Christie’s appearance Monday in Cuyahoga Falls was his first in public since being denied the role as Trump’s vice presidential candidate. He praised Trump’s selection of Pence, saying the candidate needed someone with executive experience. And in another shot at a Republican, Christie said he was pleased Trump didn’t choose “another big mouth from Congress,” apparently referring to former House Speaker Newt Gingrich, another finalist for the vice presidential choice. In 2012, Christie called Gingrich an “embarrassment.”

Late Sunday night, Christie told reporters that he was honored to have been considered for running mate but that he “wasn’t out looking for it” and had “absolutely no discontent” over Trump’s decision.

Christie, who has been friends with Trump since 2002, also sought to soften Trump’s image. He said that after Superstorm Sandy, when his wife raised money for a relief fund she ran, she called Trump for support “and it wasn’t a long phone call,” Christie said.

Christie says he's "disgusted" by president "who does not stand foursquare behind law enforcement." Repeats violence is leadership fail.

“He said, “How much does the check need to be? Just tell me and I’ll send it,” Christie told the crowd.

Trump did not make a donation to the Sandy relief fund, headed by Mary Pat Christie. He made a donation to the Drumthwacket Foundation, a separate entity dedicated to the governor’s mansion, which Mary Pat Christie also leads. The Associated Press reported that Trump donated $20,000 to the foundation between 2012, the year of the storm, and 2013.

“The governor misspoke this morning,” spokesman Brian Murray said in a statement. “Mr. Trump has given to other New Jersey charities, including the Drumthwacket Foundation.”

Trump has come under criticism in recent weeks following reports in The Washington Post examining how his philanthropic efforts have not always matched his assertions. Trump has called the stories “dishonest” and banned the newspaper from his campaign events.